Automatic injection device

ABSTRACT

An automatic injection device for delivering a dose from a medicine containing syringe includes a housing for containing the syringe, a force applicator for applying a force to eject medicine from the syringe, a trigger coupled to the force applicator for releasing the force applicator to cause an injection, a boot covering a needle attached to the syringe to protect and maintain sterility of the needle, and a mechanical interlock. The mechanical interlock prevents actuation of the trigger prior to removal of the boot. When the boot is removed, the mechanical interlock allows for actuation of the trigger.

TECHNICAL FIELD

The present invention relates to an automatic injection device fordelivering a dose of medicine to a user from a medicine containingsyringe.

BACKGROUND

Automatic injection devices are routinely used in the medical field todeliver a measured dose of medicine to a user. Due to their userfriendly design, they can be safely used by patients forself-administration, although in some circumstances they may be used bytrained personnel.

A typical automatic injection device comprises several parts which mayinclude; a syringe containing medicine, a needle fixed to the end of thesyringe, a firing mechanism including a spring (or possibly other drivemeans such as an electric motor or gas drive means), and a trigger. Thespring may be preloaded, or may be set using a dose setting mechanismsuch as a dial. The firing mechanism is activated by the trigger andforces the medicine through the needle and into the user. A mechanicallock may be provided to prevent the trigger from being accidentallypressed. This could be, for example, simply a catch that must be movedout of the way in order to access the trigger.

Single use, disposable automatic injection devices are delivered to endusers in an assembled state, with a medicine syringe contained withinthe device housing and a needle fixed to the end of the syringe. Inorder to ensure sterility of the needle, the projecting end of theneedle is contained within an rubber or elastomer “boot”. Typically, theboot forms an interference fit around the narrowed end portion of thesyringe body. The tip of the needle may penetrate the end of the boot.In the case of re-useable automatic injection devices, an end user musttypically open the housing and press a new single-use syringe intoposition. The single-use syringe will have a needle and boot already inplace.

The injection device may also comprise a boot remover to allow the enduser to easily and safely remove the boot and thereby expose the needle.Typically, the boot remover is fitted around or inside the proximal endof the device prior to insertion of the syringe into the housing. Whenthe syringe is pressed into the housing, the boot protecting the needleis captured by the boot remover, i.e. snaps into place within the bootremover. A needle shield may be further provided around the needle, suchthat the needle remains protected even after the boot has been removed.This is relevant to so-called “auto-injectors” which, in addition todriving the medicine through the needle, perform an initial step ofinserting the needle through the skin using the force provided by theinjection spring (or possible a secondary spring).

When a single use automatic injection device is to be used, a usershould first remove the boot remover and boot to expose the needle. NB.the needle remains surrounded by the needle shield at least in the caseof an auto-injector. The user will then release the mechanical lock,such that the trigger can be pressed. The user can then place theauto-injector against the surface of the skin and press the trigger topush the needle through the skin and force the medicine through theneedle. In the case of an auto-injector, a carriage and carriage-returnspring may cause the needle to be returned to a position within theneedle shield.

A problem with single use automatic injection devices occurs when a userforgets to first remove the boot, and, instead, operates the triggerwith the boot still in place. This is particularly likely in the case ofan auto-injector, where the needle and boot are not readily visible. Ifthe boot is not removed before firing, no drug is delivered to the user.Furthermore, since the medicine will now be under pressure, there is arisk that the user may inadvertently empty the syringe contents into theair if, when realising their error, they subsequently remove the boot.

A user may not have an abundance of medicine and so waste may be aserious issue. Waste may also be undesirable due to cost implications:some medicines can be extremely expensive. Therefore, there exists aneed to provide an automatic injection device that overcomes the problemof a device being fired prior to removal of a boot.

SUMMARY

It is an object of the present invention to provide an automaticinjection device that cannot be fired prior to removal of a boot.

According to an aspect of the present invention there is provided anautomatic injection device for delivering a dose from a medicinecontaining syringe. The automatic injection device comprises a housingfor containing the syringe, a force applicator for applying a force toeject medicine from the syringe, a trigger coupled to the forceapplicator for releasing the force applicator to cause an injection, aboot covering a needle attached to the syringe to protect and maintainsterility of the needle, and a mechanical interlock. The mechanicalinterlock prevents actuation of the trigger prior to removal of theboot. When the boot is removed, the mechanical interlock allows foractuation of the trigger or commencement of an actuation sequence.

The present invention overcomes problems associated with currentautomatic injection devices, where a user can accidentally fire theautomatic injection device with the boot still in place. This can resultin wasted medicine, which may be expensive to replace. The presentinvention overcomes this by providing a mechanical interlock, such thatan automatic injection device cannot be fired prior to removal of theboot.

As an option the automatic injection device comprises a boot remover forremoving the boot. The boot remover may be formed integrally with theboot. Alternatively the boot and boot remover are formed as separatediscrete components, and configured such that the boot is locked intothe boot remover upon insertion of the syringe into the housing.

In a first embodiment of the present invention, the mechanical interlockcomprises a boot remover, wherein the boot remover is configured suchthat removal of the boot remover from the housing both removes the bootfrom the needle and facilitates access to the trigger. As an option themechanical interlock comprises a cover attached to a distal end of thehousing. The cover is locked in place when the boot remover is attachedto the housing, and is removable from the housing to expose the triggeronly after removal of the boot remover and boot. As another option thecover is coupled to the distal end of the housing by one or moreflexible latches. When the boot remover has been removed, the latchesmay be disengaged and the cover removed. The boot remover may extend tocover the flexible latches when the boot remover is attached to thehousing.

In a second embodiment of the present invention, the housing comprises afirst part for containing the syringe and a second part for attachmentto the first part by a user. The mechanical interlock is configured toremove the boot upon coupling together of the first and second parts. Asan option the trigger is provided on the second part. The first andsecond parts may be coupled together by relative axial motion of theparts, for example, by engaging complimentary screw threads formed onthe first and second parts. The mechanical interlock may comprise a rodcoupled to the first part of the housing and slideable relative theretoin an axial direction. The rod has a distal end that engages with thesecond part in order to axially displace the rod upon coupling togetherof the first and second parts. The rod has a proximal end that iscoupled to the boot in order to remove the boot. As an option, the rodis coupled to the boot by way of the boot remover. As an option, thefirst part of the housing defines a channel within which the rod isslideably mounted. As an option the boot remover may comprise a peg thatprotrudes into the channel for engaging with the rod upon couplingtogether of the first and second parts in order to push the boot removeroff of the housing. Alternatively, the housing comprises a springcoupled to the rod in order to return the proximal end of the rod intothe channel upon disconnection of the first and second parts.

In a third embodiment of the present invention, the mechanical interlockcomprises a rod coupled to the boot remover and a trigger lock engagingwith the trigger and with said rod. The mechanical interlock isconfigured such that removal of the boot results in rotation of the rodthereby releasing the trigger lock. The rod may have a helical trackextending axially therealong and a peg is provided on the boot removerto engage with said track such that the rotation of the rod is caused bythe axial motion of the peg as the boot remover is removed. As an optionthe boot remover may comprise a key and the housing may comprise anaxially extending track. The key and axially extending track arearranged such that the key engages with the axially extending track toprevent rotation of the boot remover prior to removal of the bootremover.

In a fourth embodiment of the present invention, the mechanicalinterlock comprises a rod coupled to the boot remover and a trigger lockengaging with the trigger and with said rod. The mechanical interlock isconfigured such that removal of the boot results in rotation of the rodthereby releasing the trigger lock. A torsion spring is coupled betweenthe rod and the hosing to provide a rotational bias to the rod. A latchis provided on the boot remover to prevent rotation of the rod until theboot remover has been removed. As an option the rod comprises a pin forengaging with the latch. As an option the boot remover may comprise akey and the housing may comprise an axially extending track. The key andaxially extending track are arranged such that the key engages with theaxially extending track to prevent rotation of the boot remover prior toremoval of the boot remover.

In a fifth embodiment of the present invention, the housing comprises afirst part for containing the syringe and a second part for attachmentto the first part by the user. The mechanical interlock is provided bythe boot remover such that, when attached to the first and second parts,the boot remover holds the first and second parts in a non-useableconfiguration and removal of the boot remover allows the first andsecond parts to be brought together into a useable configuration. As anoption, there is provided a hinge that rotatably couples the first andsecond parts together. The mechanical interlock may further comprise atrigger lock for preventing actuation of the trigger when the device isin the non-useable configuration whilst allowing actuation of thetrigger when the device is in the useable configuration. The triggerlock may comprise an elongate plate mounted to the first part by a pivotaxle. There may be a biasing mechanism acting on the plate such that,when in the non-usable configuration, the plate prevents actuation ofthe trigger. When the device is brought together into a useableconfiguration, the plate is rotated about said axle to free the trigger.

Further aspects of the present invention are set out in the accompanyingclaims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows a cross-section through an auto-injector according to afirst embodiment;

FIG. 2 shows a cross-section through the auto-injector of FIG. 1 with aboot remover partially removed;

FIG. 3 shows a cross-section through the auto-injector of FIG. 1 with atrigger cover partially removed;

FIG. 4 shows a perspective view of an auto-injector according to asecond embodiment;

FIG. 5 shows a perspective view of the auto-injector of FIG. 4 with aboot remover partially removed;

FIG. 6 shows a close up perspective view of a proximal end of theauto-injector of FIG. 4;

FIG. 7 shows a further close up perspective view of a proximal end ofthe auto-injector of FIG. 4 with boot remover removed;

FIG. 8 shows a cross-section through an auto-injector according to athird embodiment;

FIG. 9 shows a perspective view of a boot remover according to an optionof the third embodiment;

FIG. 10 shows a side view of the boot remover of the third embodimentengaging with a rod;

FIG. 11 shows a close up perspective view of the distal end of theauto-injector of FIG. 8;

FIG. 12 shows a further close up perspective view of the distal end ofthe auto-injector of FIG. 8;

FIG. 13 shows a further close up perspective view of the distal end ofthe auto-injector of FIG. 8;

FIG. 14 shows a cross-section through an auto-injector according to afourth embodiment;

FIG. 15 shows a perspective view of a boot remover engaging with a rodaccording an example of the fourth embodiment;

FIG. 16 shows up perspective view of the distal end of the auto-injectorof FIG. 14;

FIG. 17 shows a side view of the distal end of the auto-injector of FIG.14;

FIG. 18 shows a cross-section through an auto-injector according to afifth embodiment;

FIG. 19 shows a cross-section through the auto-injector of FIG. 18, witha boot remover removed;

FIG. 20 shows a cross-section through the auto-injector of FIG. 18, anda side view of said auto-injector;

FIG. 21 shows a perspective view of a latch according to an option ofthe fifth embodiment;

FIG. 22 shows a cross-section view of a trigger lock according to anoption of the fifth embodiment;

FIG. 23 shows a cross-section view of a trigger lock according to anoption of the fifth embodiment in a different configuration;

FIG. 24 shows a perspective view of a trigger lock according to anoption of the fifth embodiment;

FIG. 25 shows a close up perspective view of the auto-injector of FIG.18;

FIG. 26 shows a perspective view of the auto-injector of FIG. 18;

FIG. 27 shows a cross-section view of an auto-injector according to asixth embodiment;

FIG. 28 shows a cross-section view of the auto-injector of FIG. 27 witha boot remover removed;

FIG. 29 shows a cross-section view of the auto-injector of FIG. 27 whenthe trigger is pressed and the device is not pressed against the skin;

FIG. 30 shows a cross-section view of the auto-injector of FIG. 27 beingactivated;

FIG. 31 shows a cross-section view of an auto-injector according to aseventh embodiment;

FIG. 32 shows a cross-section view of the auto-injector of FIG. 31 witha boot remover removed;

FIG. 33 shows a cross-section view of the auto-injector of FIG. 31 whenpressed against the skin;

FIG. 34 shows a cross-section view of the auto-injector of FIG. 31 beingactivated;

FIG. 35 shows a cross-section view of an auto-injector according to aneighth embodiment;

FIG. 36 shows a cross-section view of the auto-injector of FIG. 35following removal of a boot remover;

FIG. 37 shows a cross-section view of the auto-injector of FIG. 35 whenpressed against the skin;

FIG. 38 shows a cross-section view of the auto-injector of FIG. 35 withthe trigger depressed;

FIG. 39 shows alternative views of a locking mechanism;

FIG. 40 shows a cross-section view of an auto-injector according to aninth embodiment;

FIG. 41 shows a cross-section view of the auto-injector of FIG. 40following removal of a boot remover;

FIG. 42 shows a cross-section view of the auto-injector of FIG. 40following removal of a boot remover;

FIG. 43 shows a cross-section view of the auto-injector of FIG. 40 whenpressed against the skin;

FIG. 44 shows a cross-section view of the auto-injector of FIG. 40 beingactivated;

FIG. 45 shows a cross-section view of the auto-injector of FIG. 40 afteractivation;

FIG. 46 shows a cross-section view of an auto-injector according to atenth embodiment;

FIG. 47 shows a cross-section view of the auto-injector of FIG. 46 withthe boot remover removed;

FIG. 48 shows a cross-section view of the auto-injector of FIG. 46 whenpressed against the skin;

FIG. 49 shows a further cross-section view of the auto-injector of FIG.46 when pressed against the skin;

FIG. 50 shows a further cross-section view of the auto-injector of FIG.46;

FIG. 51 shows a cross-section view of a locking mechanism according toan eleventh embodiment;

FIG. 52 shows a cross-section view of the locking mechanism afterdisengagement;

FIG. 53 shows a cross-section view of the locking mechanism with thetrigger depressed;

FIG. 54 shows a perspective view of a release element according to atwelve embodiment of the present invention;

FIG. 55 shows a perspective view of a trigger according to a twelfthembodiment of the present invention;

FIG. 56 shows a cross section of the twelfth embodiment;

FIG. 57 shows a cross section of the twelfth embodiment;

FIG. 58 shows a cross section of the twelfth embodiment;

FIG. 59 shows a boot remover of the twelfth embodiment;

FIG. 60 shows a top cross sectional view and side view of anauto-injector according to thirteenth embodiment of the presentinvention;

FIG. 61 shows a top cross sectional view and side view of theauto-injector of FIG. 60 with the boot remover remvoed;

FIG. 62 shows a top cross sectional view and side view of theauto-injector of FIG. 60 when pressed against the skin;

FIG. 63 shows a top cross sectional view and side view of theauto-injector of FIG. 60 when activated;

FIG. 64 shows a cross sectional view of an auto-injector according tofourteenth embodiment of the present invention;

FIG. 65 shows a cross sectional view of the auto-injector of FIG. 64with the boot remover removed and the button depressed;

FIG. 66 shows a cross sectional view of the auto-injector of FIG. 64when pressed against the skin;

FIG. 67 shows a cross sectional view of the auto-injector of FIG. 64when the button is depressed and the device is pressed against the skin;and

FIG. 68 shows a cross sectional view of the auto-injector of FIG. 64once activated.

DETAILED DESCRIPTION

Embodiments to be described aim to provide an automatic injection devicethat cannot be fired until a boot protecting the syringe needle has beenremoved. The aim is to prevent the problem of wasted medicine and userfrustration that may otherwise occur. Embodiments are described in thecontext of an auto-injector, that is an automatic injection device thathas a spring or springs that not only drives the injection of medicine,but also pushes the needle into the patient's skin. Such a device isreferred to as an auto-injector. However, the skilled person willappreciate that the approach may also be applied to automatic injectiondevices that only drive medicine delivery and do not push the needleinto the skin.

With reference to FIGS. 1 to 3, there will now be described a firstembodiment, referred to here as the “enclosed button auto-injector”. Toassist with an understanding of this and further embodiments describedbelow it is helpful to define a “proximal” end of the auto-injector asbeing the end that is closest to the patient's skin when in use, and a“distal” end as being the end furthest from the patient's skin.

FIG. 1 shows a cross-sectional view of an enclosed button auto-injector101 comprising a needle 102, syringe 103, boot remover 104, boot 111,trigger 105, trigger cover 106, and housing 107. The auto-injector has aproximal end 112 and a distal end 113. The housing 107 houses the needle102 for piercing a user's skin, and the syringe 103 for containingmedicine. Activation of the trigger 105 actuates a firing mechanism 108.The firing mechanism 108 drives the needle into the skin, and forces themedicine through the needle and into the user. Although not described indetail, the device also includes a carriage 114 and carriage returnspring 115 within which the syringe 103 is mounted.

To prevent the user from accidentally activating the trigger 105, thetrigger cover 106 is removably attached to the housing 107 such that itcovers the trigger 105. This provides a physical barrier that preventsthe user from accidentally activating the trigger 105. Any suitablemechanical interlock for preventing activation of the trigger 105, suchas a trigger lock, may be used instead of the trigger cover 106. Whenthe user wishes to use the enclosed button auto-injector 101, he or shemust first remove the trigger cover 106 in order to access the trigger105.

The trigger cover 106 may be secured to the housing 107 by any suitableconnection type. For example, in FIGS. 1 and 2 the trigger cover 106 hasridges 109 for slotting into shoulders 110 formed in the housing 107.

The boot 111 is arranged to prevent contamination of the needle 102. Theboot remover 104 is connected to the boot, and facilitates removal ofthe boot. The boot remover 104 extends over the outer surface of thehousing 107 and over the ridges 109 of the trigger cover 106. By doingso, the boot remover 104 prevents any lateral displacement of ridges109, and therefore prevents the ridges 109 from being moved out of theshoulders 110, preventing removal of the trigger cover 106. The bootremover 104 may provide support to the ridges 109, holding them in placewithin the shoulders 110.

FIG. 2 shows the boot remover 104 partially removed from the housing107, no longer preventing the ridges 109 from lateral movement. Theridges 109 are pre-stressed and splay outwardly upon removal of the bootremover 104 to disengage from the shoulders 110. In an alternativeconfiguration, the ridges may by displaced outwardly by a separatebiasing mechanism, e.g. a spring. FIG. 3 shows the boot remover 104totally removed from the device 101, and the trigger cover 106 partiallyremoved. As a result, the trigger 105 is now exposed.

This arrangement forces a user to perform the step of removing the boot111 using the boot remover 104 before pressing the trigger 105. By doingso, accidentally activating the enclosed button auto-injector 101 whilethe boot 111 is still in place is not possible.

This example is but one of many ways in which the boot remover 104 canprevent removal of the trigger cover 106. For example, the boot remover104 may act as an interlock to a button, where the button may be used tofacilitate removal of the trigger cover 106.

With reference to FIGS. 4 to 7, there will now be described a secondembodiment, referred to here as the “embedded rod auto-injector”.

FIG. 4 illustrates an embedded pin or rod auto-injector 201, comprisinga firing mechanism housing 202, a syringe housing 203 containing asyringe, needle and boot (not shown), and a boot remover 204. Initially,the firing mechanism housing 202 is separate from the syringe housing203, and therefore actuation of the firing mechanism within the firingmechanism housing 202 will not actuate the injection. On assembly of theembedded rod auto-injector 201, a lip 205 on the firing mechanismhousing 202 displaces a rod 207 residing in a channel 206 in the syringehousing 203. Assembly may be achieved by screwing the firing mechanismhousing 202 into the syringe housing 203.

FIG. 5 shows the firing mechanism housing 202 fully engaged with thesyringe housing 203. The lip 205 has displaced the rod 207, which has inturn displaced the boot remover 204, removing it from the syringehousing 203. As a result, the boot will be removed before theauto-injector 201 can be actuated. FIG. 6 shows a close up view of therod 207 displacing the boot remover 204.

The boot remover 204 may have a peg 208 that protrudes into the channel206 for engaging with the rod, shown in FIG. 7. This arrangement ensuresthat the boot remover 204 can be displaced and ejected withoutsubsequent protrusion of the rod 207, which may otherwise lead to anobstruction when administering an injection. FIG. 7 also shows a track209 running along the inner surface of the syringe housing 203, forreceiving a ridge (not shown) formed on the boot remover 204, ensuringproper alignment of the boot remover 204.

The embedded rod auto-injector 201 may comprise a spring located withinthe syringe housing 203 that acts to push the rod 207 backwards (towardfiring mechanism housing 202) in order to ensure that the rod 207returns from the protruding position upon disassembly. This is relevantin particular to a re-useable device.

With reference to FIGS. 8 to 13, there will now be described a thirdembodiment, referred to here as the “helical linkage auto-injector”.

FIG. 8 shows a cross-section of a helical linkage auto-injector 301,comprising a boot remover 302, boot 312, housing 303, trigger 304 andtrigger lock 305.

The boot remover 302 has a radially projecting peg 306 and a key 307.The housing 303 has an axial track (not shown) for receiving the key307, and is arranged to prevent rotation of the boot remover 302 whilethe key 307 is engaged with the axial track. Any number of ways can beused to prevent rotation of the boot remover 302 while it is attached tothe helical linkage auto-injector 301. The use of a key 307 and axialtrack is just one of many possible alternatives.

The housing 303 contains a rod 308 with a helical track 310 (not shownin FIG. 8) running around its circumference. The helical track 310 isarranged to receive the peg 306. Note that when the peg 306 is engagedwith the helical track 310, the connection between the peg 306 andhelical track 310 may be sufficient to prevent rotational movement ofthe boot remover 302. The key 307 and axial track may then not berequired. At one end of the rod 308 there is a trigger lock 305 forpreventing actuation of the trigger 304. The trigger lock 305 featuresis shaped such that, in one orientation of the rod 308 and trigger lock305, the trigger 304 cannot be activated, but, when the rod and triggerlock are rotated 180 degrees, the trigger 304 can be activated. Theshape may be a stepped shape for example. FIG. 9 shows a perspectiveview of the boot remover 302, showing the peg 306 and a key 307, whilstFIG. 10 shows the peg 306 engaging with the helical track 310 on the rod308.

FIG. 11 shows a close up view of the trigger 304 and trigger lock 305.The trigger 304 has a lip 311 that abuts the trigger lock 305, andprevents downward motion of the trigger 304. When the boot 312 isremoved using the boot remover 302, the axial motion of the peg 306causes the rod 308 to rotate due to the interaction between the peg 306and helical track 310. The trigger lock 305, being connected to the rod308, also rotates.

FIG. 12 shows a close up view of the trigger 304 and trigger lock 305after the boot remover 302 has been removed. The trigger lock 305 nolonger blocks the path of the lip 311, allowing the trigger 304 to befreely pushed downwards, activating the auto-injector. FIG. 13 shows thetrigger 304 following actuation.

The helical linkage auto-injector 301 cannot be fired while the bootremover 302 is still in place. As the boot remover 302, along with theboot 312, is removed, the trigger lock 305 is disengaged. A user canthen press the trigger 304 and activate the auto-injector 301.

With reference to FIGS. 14 to 17, there will now be described a fourthembodiment, referred to here as the “spring loaded lock auto-injector”.

FIG. 14 shows a cross sectional view of a spring loaded lockauto-injector 401, comprising a boot remover 402, boot 412, housing 403,trigger 404 and trigger lock 405. The boot remover 402 has a latch 406and one or more keys 407 (not shown). The housing has one or more alinear, axially extending tracks (not shown) for engaging with the keys405. This arrangement restricts rotation of the boot remover 402 priorto removal. Any number of ways can be used to prevent rotation of theboot remover 402 while attached to the spring loaded lock auto-injector401.

The housing 403 contains a rod 408 with a pin 409 for engaging with thelatch 406. The housing 403 also contains a torsion spring 410 thatconnects to the rod 408, providing a torque to the rod 408 when the rodis rotationally displaced from a given orientation. At one end of therod 408 there is a trigger lock 405 for preventing actuation of thetrigger 404. The trigger lock 405 is shaped such that, in oneorientation, the trigger 404 cannot be activated, but, when the triggerlock 405 is rotated by 180 degrees, the trigger 404 can be activated.This may be facilitated by a stepped feature formed in the trigger lock405. In the auto-injector's unarmed state, the rod is rotationallydisplaced such that a torque is applied to the rod 408 by the torsionspring 410, the rod 408 being held in place by the pin 409 being engagedwith the latch 406. A perspective view of the latch and pin is shown inFIG. 15.

FIG. 16 shows close up view of the trigger 404 and trigger lock 405 inan unarmed position. The trigger 404 has a lip 411 that abuts thetrigger lock 405, preventing downward motion of the trigger 404.

When the boot remover 402 is removed, the pin 409 disengages with thelatch 406, allowing the rod 408 and trigger lock 405 to rotate due tothe torque applied by the torque spring 410. When the rod 408 andtrigger lock 405 reach their final position, the trigger lock 405 nolonger prevents the trigger 404 from being pressed.

FIG. 17 shows a close up of the trigger 404 and trigger lock 405 in anarmed position. It will be apparent that rotation of the rod 408 hascaused the trigger lock 405 to be rotated such that it no longer blocksthe path of the lip 411, allowing the trigger 404 to be freely pusheddownwards, activating the auto-injector 401.

The trigger lock in the helical linkage auto-injector and the springloaded lock auto-injector have been described as having a trigger lock(305; 405) that is arranged to abut the trigger, preventing axial motionof the trigger (304; 404). It is noted that other trigger preventionmechanisms may be used instead. For example, the trigger lock may be acover that prevents access to the trigger, wherein rotation of the rodcauses the cover to move to into a position such that it does notprevent access to the trigger.

With reference to FIGS. 18 to 26, there will now be described a fifthembodiment, referred to here as the “hinged auto-injector”. FIG. 18shows a cross sectional view of such a hinged auto-injector 501,comprising a boot remover 502, boot 514, syringe housing 503, trigger504, firing mechanism housing 505, hinge 506 and needle 507. Whenfolded, the hinged auto-injector 501 is in an unarmed position, with theboot remover 502 covering both the trigger 504 and the needle 507. Inorder to use the hinged auto-injector 501, the boot remover 502 mustfirst be removed. The hinged auto-injector 501 can then be unfolded intoa firing position.

FIG. 19 shows the hinged auto-injector 501 with the boot remover 502 andboot 513 removed, but still in the folded configuration. FIG. 20 showsthe hinged auto-injector 501 unfolded, as both a cross-section and inplan. A latch 508 may be used to lock the hinged auto-injector 501 inthe unfolded position.

FIG. 21 shows a close up view of the latch 508. Note that the latch 508may reside on either the firing mechanism 505 or the housing 503. Othersuitable mechanisms for locking the hinged auto-injector 501 in positionwill be readily apparent.

The hinged auto-injector 501 may further comprise a mechanism thatprevents actuation of the trigger 504 before the hinged auto-injector501 has been fully unfolded. An example of such a mechanical interlockcomprises a trigger lock comprising an elongate plate 509, shown in FIG.22. The elongate plate 509 features a boss 510 for preventing downwardmotion of the trigger 504: FIG. 22 illustrates the “locked” position.The elongate plate 509, upon unfolding of the auto-injector, is causedto pivot about a central pivot axis from a position in which downwardmotion of the trigger 504 is prevented into one in which downward motionof the trigger is possible. FIG. 23 shows the elongate plate 509 in anunlocked position after unfolding of the device.

The elongate plate 509 is shown in more detail in FIG. 24. A front endof the trigger lock features an angled face 511 that acts as a springand holds the elongate plate 509 in a locked position. The elongateplate 509 is mounted on a central pivot axle 512. As shown in FIG. 25,interaction with a second latch 513 on the housing 503 causes the angledface 511 to be pressed into the firing mechanism housing 505. Thisaction causes the elongate plate 509 to pivot about the pivot axle 506,causing the boss 510 to move clear of the path of the trigger 504. FIG.26 shows the hinged auto-injector 501 in a locked position, with theelongate plate 509 disengaged, and the latch 508 engaged.

With reference to FIGS. 27 to 30, there will now be described a sixthembodiment, referred to here as the “floating auto-injector”. FIG. 27shows a cross sectional view of such a floating auto-injector 601,comprising a boot remover 602, housing 603, and trigger 604 attached tothe housing 603. The housing 603 houses a syringe, needle 609, andfiring mechanism, which are not shown FIG. 27. The floatingauto-injector 601 also comprises an outer casing 605, within which thehousing 603 sits. The housing 603 is axially movable with respect to theouter casing 605.

The outer casing 605 has a first opening located at a proximal end and asecond opening located at a distal end. The first opening is ofsufficient size to allow the proximal end of the housing to passthrough. The second opening is of sufficient size to allow the triggerto pass through. A spring 606 acts between the housing 603 and the outercasing 605 to bias the housing 603 in a distal direction.

The boot remover 602 is arranged to remove the boot (not shown) andfurther arranged such that when it is attached to the housing 603, theboot remover 602 holds the housing 603 forward in a first proximalposition. While the housing 602 is held forward in the first position,the trigger 604 is held within the outer casing 605, and access to thetrigger 604 is restricted. The floating auto-injector 601 may alsocomprise an elastic membrane 607 which covers the distal opening,preventing access to the inside of outer casing 605.

FIG. 28 shows the floating auto-injector 601 once the boot remover 602has been removed. With the boot remover 602 no longer holding thehousing 603 in place, the spring 606 pushes the housing 603 distally toa second position, such that the trigger 604 extends through distalopening, stretching the elastic membrane 607, and making the trigger 604accessible to a user.

When the floating auto-injector 601 is not pressed against the user'sskin, pressing the trigger 604 pushes the housing into the outer casing605 such that the proximal end of the housing 604 exits the proximal endof the outer casing 605. The housing 604 is moved towards its firstposition, until the trigger 604 is no longer accessible. The forcerequired to move the trigger 604 relative to the housing 603 is greaterthan the force required to move the housing 603 relative to the outercasing 605. Therefore, pushing the trigger 604 moves the housing 603through the outer casing 605, and does not activate the floatingauto-injector 601. This is shown in FIG. 29.

FIG. 30 shows the floating auto-injector 601 when the outer casing 605is pressed against the skin 608. By applying pressure to the trigger 604in a proximal direction, the proximal end of the housing 603 is pressedagainst the skin 608. With both the housing and outer casing 605 pressedagainst the skin, the two cannot move relative to one another, and sothe force applied to the trigger 604 axially moves the trigger 604relative to the housing 603, activating the floating auto-injector 601.

FIGS. 31 to 34 show a seventh embodiment, the seventh embodiment beingan alternative arrangement of the floating auto-injector embodiment. Thealternative floating auto-injector 701 is structurally similar to thefloating auto-injector 601, but whereas the floating auto-injector 601has a spring 601 that urges the housing 603 distally with respect to theouter casing 605, the alternative floating auto-injector 701 has aspring 706 which urges the housing 703 proximally with respect to theouter casing 705. When urged forward by the spring 706, access to thetrigger 704 is restricted, as shown in FIGS. 31 and 32. In order toaccess the trigger 704, a proximal ending of the housing 703 must bepressed against a user's skin in order for the housing to move rearwardrelative to the outer casing 705, as in sixth embodiment. When the bootremover 702 is attached, the boot remover 702 covers a proximal end ofthe outer casing 705, such that the housing 703 cannot be pressedagainst the user's skin. Therefore, in order to activate the device 701,the user must first remove the boot remover 702, exposing the proximalend of the housing 703, and then press the proximal end of the housing703 against the skin, such that the trigger 704 becomes accessible. Thedevice can then be activated by pressing the trigger.

With reference to FIGS. 35 to 39, there will now be described a eighthembodiment, referred to here as the “toothed wheel auto-injector”. FIG.35 shows a cross sectional view of such a toothed wheel auto-injector801, comprising a boot remover 802, housing 803, trigger 804 and skinsensor 805. The housing is arranged to house a syringe carrying needleand force applicator (not shown). When the boot remover 802 is attachedto the device 801, the boot remover 802 abuts the trigger 804,preventing the trigger 804 from being displaced relative to the housing803. FIG. 36 shows the toothed wheel auto-injector 801 following removalof the boot remover 802.

The toothed wheel auto-injector 801 further comprises a rotatable shaft806 which is coupled to a plunger 807. The plunger 807 is coupled to thetrigger 804 such that by pressing the trigger 804, the plunger is pushedinto a bung of a syringe. The plunger 807 may be driven via a drivespring (not shown), or any other means.

The rotatable shaft 806 is connected to the plunger 807 by a flexiblemember 808, such as string. The rotatable shaft 806 has two toothedportions 809, 810 which extend circumferentially around the outersurface of the rotatable shaft 806. The toothed portions 809, 810 arearranged to engage with locking levers 811, 812, which prevent rotationof the shaft 806. When the shaft 806 is rotationally fixed, the plunger807 is restricted from axially movement due to the connection via theflexible member 809. Alternatively, the flexible member 808 may beattached directly to the trigger 804, preventing axial movement of thetrigger 804 when the locking levers 811, 812 are engaged.

The skin sensor 805 is arrange to extend beyond a proximal end of thehousing 803, and further arranged such that when the skin sensor 805 ispressed against the skin, the skin sensor 805 is pushed into the housing803. When pushed into the housing 803, the skin sensor 805 acts on thelocking levers 811, 812 via legs 813, 814, disengaging the lockinglevers 811, 812 from the toothed portions 809, 810 of the shaft 806,allowing rotation of the shaft 806.

The locking levers 811, 812 are pivotally attached to the housing 803via pivot points 814, 815. The pivot points 815, 816 are located betweena part of the levers where the legs 813, 814 of the skin sensor 805 act,and a part of the levers that engage with the toothed portions 809, 810.Therefore, when pressed against the skin, the skin sensor 805 causes thelocking levers 811, 812 to pivot, disengaging them from the toothedportions 809, 810, and allowing the device 801 to be actuated. FIG. 37shows the skin sensor having been pushed into the housing, such that thelocking levers 811, 812 have pivoted about the pivot points 815, 816,disengaging from the shaft 806. FIG. 38 shows the trigger 804 beingpushed into the housing. FIG. 39 shows alternative views of the plunger807, and shaft 806.

With reference to FIGS. 40 to 45, there will now be described a ninthembodiment, referred to here as the “toothed element auto-injector”.FIG. 40 shows a cross sectional view of such a toothed elementauto-injector 901, comprising a boot remover 902, housing 903, trigger904 and outer casing 905.

The boot remover 902 abuts the trigger 904, prior to removal of the bootremover 902. This prevents the trigger 904 from being displaced relativeto the outer casing 905 and/or the outer casing 905 to activate thedevice 901. FIG. 41 shows the boot remover 902 removed.

The housing 903 is located within the outer casing 905 and a part of thehousing 903 protrudes from a proximal end of the outer casing 905, suchthat it can be pressed against the skin. The outer casing 905 comprisesa drive spring 906 and plunger 907, for acting on a bung or plunger of asyringe 908 contained in the housing 903. Pressing the trigger 904activates the drive spring 906, which drives the plunger 907.

The device 901 further comprises two locking elements 909, 910 axiallyfixed within the outer casing 905. The locking elements 909, 910 haveinterlocking teeth which engage with interlocking teeth on the plunger907, preventing axial movement of the plunger 907. When the lockingelements 909, 910 are engaged, the device 901 cannot be activated (FIG.42).

The housing 903 is axially moveable relative to the outer casing 905,and when pressed against the user's skin, the housing 903 is pushed intothe outer casing 905 (FIG. 43).

The outer casing 905 comprises biasing springs 911 which bias thelocking elements 909, 910 against the plunger 907 such that the teethinterlock. While teeth have been described, it will be understood by theskilled person that any interlocking feature may be used.

The housing 903 has two angled surfaces 912, 913 which interact with twoangled surfaces 914, 915 on the locking elements 909, 910, when thehousing 903 is pressed into the outer casing 905. These angled surfacescause the locking elements to be radial displaced, disengaging them fromthe plunger 907 (FIG. 43-45).

Therefore, the boot remover must first be removed and then the device901 pressed against the skin before pressing the trigger 904 activatesthe device 901, driving a needle 916 into a user and dispensing medicinecontained in the syringe 908.

With reference to FIGS. 46 to 50, there will now be described a tenthembodiment. FIG. 46 shows a cross sectional view of an auto-injector1001 according to the tenth embodiment. The auto-injector 10001comprises a boot remover 1002 for removing a boot 1002 a, housing 1003,trigger 1004 and skin sensor 1005. The housing 1003 houses a syringecarrying medicine, a needle, and drive mechanism (not shown) for drivingthe needle into a user's skin, and dispensing the medicine.

The skin sensor 1005 extends proximally from the housing 1002, and isarranged to be pressed against the user's skin. The boot remover 1002covers the skin sensor 1005 such that the skin sensor 1005 cannot bepressed against the skin. With the boot remover 1002 removed (FIG. 47),the skin sensor 1005 can be pressed against the skin. The skin sensor1005 has an elongated leg 1006 which abuts a corresponding elongated leg1007 on the trigger 1004. The abutment prevents the trigger 1004 frombeing axially displaced.

The skin sensor 1005 further comprises a helical keyway 1008 whichengages with a boss 1009 on an inner surface of the housing 1003. Whenthe skin sensor 1005 is pressed against the skin, the skin sensorrotates into the housing due to the boss 1009 following the helicalkeyway 1008 (FIGS. 48 and 49). This allows the elongated leg 1006 of theskin sensor 1005 to disengage from the elongated leg 1007 of the trigger1004, thereby allowing displacement of the trigger.

With reference to FIGS. 51 to 53, there will now be described aneleventh embodiment. FIG. 51 shows a cross sectional view of a distalend of an auto-injector 1101 according to the eleventh embodiment. Theauto-injector 11001 comprises a boot remover (not shown) for removing aboot, housing 1102, trigger 1103 and skin sensor 1104. As with theeighth embodiment, the skin sensor 1104 is arranged to be pressedagainst the skin, such that it enters the housing 1102. The boot removeris arranged such that, prior to removal, it covers a proximal end of theskin sensor 1104, preventing it from being pressed against the skin andinto the housing 1102. The trigger 1103 is prevented from axial movementin the proximal direction due to an abutment between the trigger 1103and two flexible legs 1105, 1106 fixed on the inside of the housing1102.

When the boot remover is removed, the skin sensor 1104 is pressedagainst the skin, such that it moves axially into the housing 1102. Thea distal end of the skin sensor 1104 pushes against the flexible legs1105, 1106, causing them to deform (FIG. 52). Once deformed, theflexible legs 1105, 1106 no longer abut the trigger 1103, allowingactivation of the device 1101 (FIG. 53).

With reference to FIGS. 54 to 59, there will now be described a twelveembodiment. FIG. 55 shows a trigger 1201 for activating an automaticinjection device (not shown). The trigger 1201 has three latches 1202which extend from the trigger 1201, and are arranged to project throughslots 1203 of a housing 1204 of the auto-injector (FIG. 56). Thisengagement prevents actuation of the trigger 1201.

The auto injector has three release elements 1205 (a release element isshown in FIG. 54 from a side view and front view). The release elements1205 have a de-latching portion 1206, which feature a raised, angledsurface 1207 for engaging with the latch 1202 of the trigger 1201. Therelease elements extend beyond a proximal end of the housing 1204 andare arranged such that, when the auto-injector is pressed against theskin, the release elements 1205 are pushed into the housing 1204 and thede-latching portions 1206 engage with, and slide past, the latches 1205so as to press the latches back through the slots 1203 and allow thetrigger 1201 to be actuated (FIGS. 57 and 58).

The release elements 1205 are fixed to the housing 1204, and haveintegral spring elements 1207 between the attachment to the housing andthe de-latching portion 1206. The spring elements 1207 are arranged tocompress when the release elements 1205 are pressed against the skin.Any number of release elements may be used. The release elements 1205are distributed evenly around a circumference having its centre along anaxial direction of the housing 1204. This can be seen from FIG. 55,where the three latches 1202, which engage with the release elements1205, are distributed evenly.

FIG. 59 shows a boot remover 1208 which removes the boot (not shown),and covers the release elements 1205. The boot remover 1208 must beremoved before the release elements 1205 can be pressed against theskin.

With reference to FIGS. 60 to 63, there will now be described athirteenth embodiment. FIGS. 60 to 63 show a top cross sectional view ofan auto-injector of the thirteenth embodiment, and a partial crosssectional side view. The auto-injector 1301 of the thirteenth embodimentcomprises a housing 1302 which houses a syringe and needle, and drivemechanism (not shown) for activating the device 1301; a trigger 1303coupled to the housing 1302, and arranged to activate the drivemechanism; a boot remover 1304 for removing the boot and covering theproximal end of the device 1301; a skin sensor 1305 protrudingproximally beyond the housing 1302 and an out casing 1306; and anelliptical flexible collar 1307 axially fixed to the housing 1302, andlocated between the trigger 1303 and the housing 1302.

The elliptical flexible collar 1307 is arranged to sit around a part ofthe trigger 1303, and prevent the trigger 1303 from being fullydepressed when in a first configuration, preventing activation of thedevice 1301. In the first configuration the collar 1307 has a minor axis1308 which is shorter than the diameter of an upper part of the trigger1309. This prevents the trigger 1303 from being fully depressed into thehousing 1302 (FIG. 60 shows the device 1301 with the boot remover 1304attached, and 61 shows the device with the boot remover removed). Notethat while the trigger is described as having a diameter, and the collaris describe as being elliptical, both may be any suitable shape suchthat deformation of the collar allows the trigger to pass through.

The skin sensor 1305 has an angled surface 1310 at its distal end. Whenthe skin sensor 1305 is pressed against the skin (FIG. 62), it is movedinto the outer casing 1306, and the angled surface 1310 pushes againstthe vertices defining the major axis, so as to deform the ellipticalflexible collar 1307. The deformation causes the minor axis to increasein length, until the trigger 1303 is no longer blocked by the collar1307. In this second configuration, the device can then be activated(FIG. 63). The boot remover 1304 covers the skin sensor 1305 prior toremoval. Once removed, the skin sensor 1305 may be pressed against theskin.

With reference to FIGS. 64 to 68, there will now be described afourteenth embodiment. FIGS. 64 to 68 show a cross section of anauto-injector of the thirteenth embodiment. The auto-injector 1401comprises a housing 1402 housing a syringe, drive mechanism (not shown),and needle 1411; an outer casing 1403 within which the housing 1402 islocated; a boot remover 1404 for removing a boot and covering theproximal end of the device 1401; and a trigger 1405.

The housing 1402 is contained within the outer casing 1403 and arrangedto be axially moveable within the outer casing 1403. The drive mechanismwithin the housing 1402 is prevented from being released and activatingthe device 1401 by being connected to flexible member 1406 which isclamped in two places.

The auto-injector 1401 further comprises a spring 1407 which actsbetween the outer casing 1403 and the housing 1402 and biases thehousing 1402 towards a proximal end of the outer casing 1403 such that apart of the housing 1402 protrudes from an opening of the proximal endof the outer casing 1403. When held in this forward position by thespring 1407, a part of the flexible element 1406 is clamped in a firstclamped position 1408 between an outer surface of the housing 1402 andan inner surface of the outer casing 1403. When the housing 1402 ispressed against the skin, the housing 1402 moves into the outer casing1403, which releases the clamp 1408 (FIG. 66).

The boot remover 1404 prevents the housing 1402 from being pressedagainst the skin, prior to removal.

The flexible element 1406 is further clamped in a second position by abutterfly valve 1409 coupled to the housing 1402. The trigger 1405 hastwo release pegs 1410, which engage with the butterfly valve 1409 whenthe trigger 1405 is displaced. This engagement opens the valve 1409,unclamping the flexible element 1406 from the second clamp (FIG. 67).The drive mechanism is no longer prevented from being released by theflexible member, and so the device 1401 is activated, driving the needle1411 and medicine into the user's skin.

The device 1401 is a further arranged, such that when the housing 1402is held in the forward position by the spring 1407, the butterfly valve1409 is held in a position which is inaccessible to the release pegs1410 of the trigger 1404. This is shown in FIG. 65, where the trigger1405 is pressed into the housing, but does not reach the valves 1410.While not shown, the trigger 1405 has limited axial movement due to astructural stop, such as a ledge within the outer casing 1403.

It will be appreciated by the person of skill in the art that variousmodifications may be made to the above described embodiments withoutdeparting from the scope of the present invention. Furthermore, whileseveral separate embodiments have been described, the skilled personwill recognise that some of these embodiments may be combined.

1-70. (canceled)
 71. An automatic injection device for delivering a dosefrom a medicine containing syringe and comprising: a housing forcontaining the syringe; a force applicator for applying a force to ejectmedicine from the syringe; a trigger coupled to the force applicator forreleasing the force applicator to cause an injection; a boot covering aneedle attached to the syringe to protect and maintain sterility of theneedle; a first mechanical interlock for preventing actuation of thetrigger prior to removal of the boot and for allowing actuation orcommencement of an actuation sequence following removal of the boot; anda second mechanical interlock for detecting pressure applied to thedevice by the user's skin following removal of the boot, and configuredto prevent actuation of the trigger in the absence of pressure and toallow actuation when sufficient pressure is detected.
 72. The automaticinjection device according to claim 71 further comprising a boot removerfor removing the boot.
 73. The automatic injection device according toclaim 72, wherein the boot remover is formed integrally with the boot.74. The automatic injection device according to claim 72, wherein theboot and boot remover are formed as separate discrete components, andconfigured such that the boot is locked into the boot remover uponinsertion of the syringe into the housing.
 75. The automatic injectiondevice according to claim 72, wherein said first mechanical interlockcomprises said boot remover, the boot remover being configured such thatremoval of the boot remover from the housing both removes the boot fromthe needle and facilitates access to the trigger.
 76. The automaticinjection device according to claim 71, wherein the trigger is attachedto the housing and is arranged to release the force applicator when thetrigger is moved axially in a proximal direction relative to thehousing, the automatic injection device further comprising an outercasing, wherein the housing is located within the outer casing, and isaxially moveable within the outer casing.
 77. The automatic injectiondevice according to claim 76, wherein the outer casing comprises a firstopening located at a proximal end and a second opening located at adistal end, wherein the housing is further arranged such that a proximalpart of the housing can pass through the proximal opening of the outercasing, and the trigger can pass through the distal opening of the outercasing.
 78. The automatic injection device according to claim 72,wherein the outer casing comprises a first opening located at a proximalend and a second opening located at a distal end, wherein the housing isfurther arranged such that a proximal part of the housing can passthrough the proximal opening of the outer casing, and the trigger canpass through the distal opening of the outer casing, and wherein theboot remover provides said mechanical interlock, the boot remover beingarranged at the proximal end of the outer casing, and being furtherarranged, prior to removal, to hold the housing in a first positiontowards the proximal end of the outer casing such that the trigger islocated within the outer casing, restricting access to the trigger. 79.The automatic injection device according to claim 78, further comprisinga biasing device acting between the outer casing and the housing, andarranged such that when the boot remover is removed, the biasing devicemoves the housing in a distal direction relative to the outer casing toa second position, such that at least a part of the trigger protrudesfrom the distal opening of the outer casing, allowing access to thetrigger.
 80. The automatic injection device according to claim 79,further arranged such that, following removal of the boot remover andboot, when the proximal end of the outer casing is placed against theskin, applying force to the trigger in a proximal direction causes theproximal end of the housing to be pressed against the skin, and thetrigger to be displaced axially relative to the housing, activating thedevice.
 81. The automatic injection device according to claim 76, thesecond mechanical interlock being provided by a biasing device actingbetween the outer casing and the housing and arranged to bias thehousing in a proximal direction relative to the outer casing and therebytend to push an end of the housing through a proximal end of the casingand restrict access to the trigger.
 82. The automatic injection deviceaccording to claim 72, wherein the trigger is attached to the housingand is arranged to release the force applicator when the trigger ismoved axially in a proximal direction relative to the housing, theautomatic injection device further comprising an outer casing, whereinthe housing is located within the outer casing, and is axially moveablewithin the outer casing, and the second mechanical interlock beingprovided by a biasing device acting between the outer casing and thehousing and arranged to bias the housing in a proximal directionrelative to the outer casing and thereby tend to push an end of thehousing through a proximal end of the casing and restrict access to thetrigger, and wherein the boot remover provides said first mentionedmechanical interlock, the boot remover being arranged at the proximalend of the outer casing and being further arranged, prior to removal, toprevent the housing from being pressed against the skin, therebyrestricting access to the trigger.
 83. The automatic injection deviceaccording to claim 71, further comprising a flexible collar axiallyfixed relative to the housing and being deformable from a firstconfiguration to a second configuration, the flexible collar when insaid first configuration preventing axial movement of the triggerrelative to the housing and when in the second configuration allowingsaid axial movement of the trigger, the flexible collar being arrangedaround a part of the trigger, and the device further comprising a skinsensor which is axially moveable relative to the housing and extendsproximally from the housing, and provides said second mechanicalinterlock by being arranged such that when the skin sensor is pressedagainst the skin, the skin sensor moves into the housing and pressesagainst the flexible collar so as to deform it from the firstconfiguration to the second configuration.
 84. The automatic injectiondevice according to claim 83, wherein the first mentioned mechanicalinterlock is provided by the boot remover covering a part of the skinsensor such that the skin sensor cannot be pressed against the skin anddisplaced relative to the housing.